A fully biodegradable film and a preparation method and application thereof

Abstract

The application discloses a kind of full biodegradable film and its preparation method and application.The full biodegradable film is with inner and outer two-layer structure, outer layer is the polyester full biodegradable material modified by epoxy modifier;Inner layer is mixed material, including polyvinyl alcohol, plasticizer, ethylene-acrylate-glycidyl methacrylate 1.5-8%, the rest is other auxiliary agent.The inner layer of film can be closely attached on glass, ceramic tile, wood, paper and metal after wetting Common material, realize close attachment, and easy to wash after uncovering film without leaving glue mark, can serve the packaging storage and transportation of these materials.

Description

Technical Field

[0001] This invention relates to the field of composite materials technology, specifically to a fully biodegradable film, its preparation method, and its application. Background Technology

[0002] Common building materials such as glass, ceramic tiles, and wood are hard and some have undergone polishing, sanding, electroplating, or painting. During handling, care must be taken to prevent bumps, scratches, and abrasions. Packaging materials such as foam boards, cardboard, and plastic films provide excellent protection for these materials and are commonly used in building material packaging. Among these, plastic film, compared to other packaging materials, offers advantages such as good adhesion, high transparency, small volume, light weight, thinness, flexibility, and resistance to breakage, making it widely used as packaging for building materials.

[0003] Common polyethylene films can be tightly adhered to smooth glass and ceramic tile surfaces by electrostatic adsorption. However, when used on metal materials or ceramic and glass surfaces with frosted finish, adhesive is often applied to the polyethylene film surface to improve the adhesion between the film and the packaged material. This brings a series of problems: (1) In order to ensure the strength of the film so that it can be torn off the packaged item, the thickness of this PE film is often up to 30 micrometers, which increases the cost of use; (2) The adhesive used is often insoluble in water. After the film is removed, the adhesive may remain on the surface of the packaged item, becoming dirt that is not easy to clean; (3) The adhesive may contain toxic volatile substances such as formaldehyde, which are easily released into the environment and cause harm; (4) Polyethylene material cannot be degraded, and large-scale use leads to environmental damage. Summary of the Invention

[0004] This invention provides a fully biodegradable film, its preparation method, and its application. The film is made by melt extrusion of polyvinyl alcohol and polyester-based fully biodegradable materials into a double-layer structure. The inner polyvinyl alcohol has adhesive properties when wet and can adhere to the surface of building materials after wetting. It is not easy to tear after drying, and the adhesive layer and structural layer are not easy to separate. This solves the problems of high cost, difficulty in removal, and difficulty in degradation caused by the existing adhesive treatment.

[0005] This invention is achieved through the following technical solutions:

[0006] The application discloses a full-biodegradable film, which is a multilayer co-extrusion film with an inner layer and an outer layer, wherein the outer layer is a polyester full-biodegradable material modified by an epoxy modifier; and the inner layer is a mixed material, wherein the raw materials of the inner layer mixed material include 50-90% of polyvinyl alcohol, 5-20% of plasticizer, 1.5-8% of ethylene-acrylate-glycidyl methacrylate, and the rest of other additives, and the polyvinyl alcohol has an alcoholysis degree of 78-99% and a polymerization degree of 3-170,000.

[0007] Preferably, the inner layer further includes polyester full-biodegradable material modified by an epoxy modifier, and the weight percentage of the polyester full-biodegradable material modified by the epoxy modifier is not more than 30%.

[0008] Preferably, the polyester full-biodegradable material modified by the epoxy modifier is modified by 0.4-0.8% of the epoxy modifier (based on the weight percentage of the outer layer); and the polyester full-biodegradable material is selected from one or two of polybutylene adipate terephthalate, polylactic acid, polypropylene carbonate, polybutylene succinate, polyglycolic acid and polycaprolactone; and the polyester full-biodegradable material includes a filling material mainly composed of the polyester full-biodegradable material.

[0009] Preferably, the epoxy modifier is an epoxy chain extender.

[0010] Preferably, the epoxy modifier is an oligomer with a molecular weight of 6000-8000 g / mol and an epoxy equivalent weight of 200-400 g / eq.

[0011] When the high-temperature water-soluble film with an alcoholysis degree of 99% is used, the inner layer will be sticky and be removed by a large amount of hot water only in hot water above 80 DEG C, and the film cannot be sticky in normal temperature water and be removed by a large amount of water. Preferably, the alcoholysis degree of the polyvinyl alcohol is 78-88%, and more preferably, the alcoholysis degree of the polyvinyl alcohol is 88%. At this time, the film can be slightly sticky in normal temperature water or be removed by a large amount of water.

[0012] Preferably, the plasticizer is glycerol. The application can also use a compound plasticizer mainly composed of glycerol and other plasticizers. The other plasticizers include but are not limited to one or more polyhydric alcohol materials such as ethylene glycol, polyethylene glycol, triethylene glycol and 1,3-propanediol.

[0013] Preferably, the weight percentage of the glycidyl methacrylate group in the ethylene-acrylate-glycidyl methacrylate is 6-10%.

[0014] The preparation method of the full biodegradable film is prepared by heating, melting and multi-layer co-extrusion, and the film is prepared by one of film blowing method, casting method and calendering method.

[0015] Specifically, the steps for preparing the full biodegradable film by the film blowing method are as follows:

[0016] (1) The polyester full biodegradable material and the epoxy modifier are weighed according to the weight, are melt-blended in a double-screw extruder, are extruded and granulated, and are dried to obtain the polyester full biodegradable material modified by the epoxy modifier as an outer layer material;

[0017] (2) The inner layer material is obtained by weighing the inner layer raw material, sufficiently mixing and uniformly the polyvinyl alcohol, the plasticizer and other additives in a high-speed stirrer, melt-blending in a double-screw extruder, and then uniformly mixing and stirring the ethylene-acrylate-glycidyl methacrylate at room temperature;

[0018] Alternatively, the inner layer material is obtained by weighing the raw material, sufficiently mixing and uniformly the polyvinyl alcohol, the polyester full biodegradable material modified by the epoxy modifier obtained in step 1), the plasticizer and other additives in a high-speed stirrer, melt-blending in a double-screw extruder, and then uniformly mixing and stirring the ethylene-acrylate-glycidyl methacrylate at room temperature;

[0019] (3) The outer layer material and the inner layer material are respectively added to a double-layer extrusion film blowing machine, the film is blown, the edges are cut, and the packaging film is wound.

[0020] The application further provides the application of the full biodegradable film in packaging of building materials, and the inner layer of the film faces the building materials and directly contacts the building materials.

[0021] Preferably, the building materials are ceramic tiles or glass.

[0022] The full biodegradable film of the application is wet and sticky, the film has an inner and outer layer structure, the outer layer is away from the packaged materials, and the inner layer is towards the packaged materials and directly contacts the packaged materials. After the surface of the packaged materials is wetted by water, the packaging film can be adhered to the surface of the materials. The inner and outer layer structure of the film and the used materials are the main structure and main materials of the film. In the case that the inner and outer layer structure and the used materials are determined, if other materials are added as an intermediate layer between the inner layer and the outer layer, the intermediate layer plays the bonding function of the inner layer and the outer layer, which should be considered as a supplement to the application; if other materials are added as a new outer layer, the original outer layer is sandwiched between the new outer layer and the inner layer as an intermediate layer, which should be considered as a supplement to the application.

[0023] The water-soluble material polyvinyl alcohol which is harmless to human body is selected as the bonding material, and the polyvinyl alcohol is compounded with the environment-friendly polyester biodegradable material by a melt extrusion method to form a biodegradable film with a double-layer structure, wherein the inner layer is the polyvinyl alcohol which has bonding property after being wetted, and the outer layer does not have bonding property. The film has no adhesion in a dry state, has certain adhesion and self-adhesion in a wet state, can be adhered to the surface of common building materials in a water state, and is not easy to tear after the water is dried. The double-layer melt extrusion method can make the film thin to save the cost, and the outer layer and the inner layer are added with an epoxy modifier and an ethylene-acrylic acid glycidyl methacrylate respectively, so that the adhesion between the outer layer and the inner layer is improved and the film is not easy to peel off, and meanwhile, the equipment and process for spraying adhesive are avoided, the process is simple and environment-friendly, the bonding material is non-toxic, water-soluble and easy to clean, and when the film is torn off and removed, even if a small amount of film or inner layer material is left on the packaged material, the adhesive mark can be removed by washing with water.

[0024] Compared with the prior art, the present application has the following advantages:

[0025] The biodegradable film has the property of wetting and adhesion, can be used in the production and packaging of building materials such as ceramic tiles and glass, is closely attached to the packaged material, and is not easy to peel off between the layers. In the production process of building materials, the surface usually needs to be cleaned with water, and the building materials also need to be dried, so the film of the present application can skip the drying step and be directly coated and packaged, since the biodegradable material used has high water permeability, the water in the package will evaporate quickly and will not remain in the package, saving drying time and energy. The adhesive of the packaging film is water-soluble polyvinyl alcohol, which can be easily removed by washing with water after the package is removed, without the need for special chemical solvent removal, non-toxic and environmentally friendly, reducing the risk of material surface being scratched and corroded in the removal process of traditional adhesive. The present application can also be used as a wrapping film to wrap goods, and then water is sprayed on the surface of the last layer to achieve self-adhesion. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a schematic diagram of the biodegradable film of the present application for peel strength test. DETAILED DESCRIPTION

[0027] The technical solutions of the present application will be described clearly and completely below in combination with the drawings in the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0028] Example 1

[0029] Experimental materials: polybutylene adipate terephthalate, A400 MF NC801, Zhuhai Jin Gene Biomaterials Co., Ltd.; polylactic acid, 4032D, Natureworks; epoxy chain extender, Joncryl ® ADR 4468 BASF SE; polyvinyl alcohol, 0588, Changchun Chemical Industry (Jiangsu) Co., Ltd.; glycerol, analytical pure, Xilong Chemical; ethylene-acrylate-glycidyl methacrylate, LOTADER AX8900 Arkema, France; antioxidant, 1010, commercially available; antioxidant, 168, commercially available.

[0030] Preparation steps of fully biodegradable packaging film (Film A):

[0031] (1) 80 parts of polybutylene adipate terephthalate, 20 parts of polylactic acid and epoxy chain extender (0.6% of the weight percentage of outer layer material) were weighed and melt blended in a twin-screw extruder, extruded and dried to obtain an outer layer material;

[0032] (2) 80 parts of polyvinyl alcohol was weighed and mixed with 20 parts of glycerol, 0.2 parts of antioxidant 1010 and 0.2 parts of antioxidant 168 in a high-speed mixer to obtain an inner layer material;

[0033] (3) The outer layer material of step (1) and the inner layer material of step (2) were added to a double-layer extrusion film blowing machine respectively, and the film was blown, the edges were cut, and the packaging film was rolled up.

[0034] Comparative Example 1

[0035] Reference Example 1, the difference is that low density polyethylene is used as the outer layer material in step (1):

[0036] (1) Low density polyethylene is used as the outer layer material (linear low density polyethylene, 7042, Maoming Petrochemical). Other steps are the same as Example 1. The prepared film is Film B.

[0037] Comparative Example 2

[0038] Use transparent tape as Film C (Wanrong).

[0039] Comparative Example 3

[0040] Use dot-and-dash preservative film as Film D (Miao Jie).

[0041] Comparative Example 4

[0042] Reference Example 1, except that in step (1), 80 parts of polybutylene adipate / terephthalate, 20 parts of polylactic acid were melt blended in a twin-screw extruder, extruded and pelletized and dried to obtain the outer layer material. Other steps were the same as Example 1. The obtained film was used as Film E.

[0043] Comparative Example 5

[0044] Reference Example 1, except that in step (2), 80 parts of polyvinyl alcohol, 20 parts of glycerol, 0.2 parts of antioxidant 1010 and 0.2 parts of antioxidant 168 were mixed well in a high-speed mixer, and then melt blended in a twin-screw extruder to obtain the inner layer material. Other steps were the same as Example 1. The obtained film was used as Film F.

[0045] Comparative Example 6

[0046] Reference Example 1, except that in step (1), no epoxy chain extender was added, and in step (2), no ethylene-acrylate-glycidyl methacrylate was added. Other steps were the same as Example 1. The obtained film was used as Film G.

[0047] Example 2

[0048] Reference Example 1, except that in step (2), the inner layer material further contained 8 parts of an epoxy-modified polyester-based fully biodegradable material, which was the outer layer material in step (1) of Example 1. The preparation steps were as follows:

[0049] (2) 80 parts of polyvinyl alcohol, 8 parts of the outer layer material in step (1), 20 parts of glycerol, 0.2 parts of antioxidant 1010 and 0.2 parts of antioxidant 168 were weighed and mixed well in a high-speed mixer, and then melt blended in a twin-screw extruder. The melt-blended product was mixed with 3 parts of ethylene-acrylate-glycidyl methacrylate in a high-speed mixer for 1 min to obtain the inner layer material; other steps were the same as Example 1. The obtained film was used as Film H.

[0050] Example 3 Peeling strength test

[0051] Experimental materials: Film A, Film B, Film C, Film D, Film E, Film F, Film G, Film H in Examples 1-2 and Comparative Examples 1-6.

[0052] Experimental method;

[0053] 1. Peeling strength test method of Film A and surface wetting material:

[0054] The inner layer of film A was adhered to the surface of a polished tile / a matte tile / a glass sheet / a wood sheet / an iron sheet / a copper sheet with a wet surface, and left to stand for 1 day. One end of the polished tile / the matte tile / the glass sheet / the wood sheet / the iron sheet / the copper sheet was fixed to the lower clamp of a tensile tester, and the unadhered portion of the film was fixed to the upper clamp of the tensile tester. The peeling test was performed at a tensile rate of 50 mm / min, and the maximum force was recorded.

[0055] The inner layer of film A was adhered to the outer layer of another film A / film B with a wet surface, and left to stand for 1 day. The unadhered portion of the film was fixed to the upper and lower clamps of a tensile tester, respectively, and the peeling test was performed at a tensile rate of 50 mm / min. The maximum force was recorded.

[0056] 2. Peeling strength test method of film A from a dry surface material

[0057] The inner layer of film A was adhered to the surface of a polished tile with a dry surface, and left to stand for 1 day. One end of the polished tile was fixed to the lower clamp of a tensile tester, and the unadhered portion of the film was fixed to the upper clamp of the tensile tester. The peeling test was performed at a tensile rate of 50 mm / min, and the maximum force was recorded.

[0058] 3. Peeling strength test method of film B from a polished tile with a wet surface, as above.

[0059] 4. Peeling strength test method of film C from a polished tile with a wet surface, from a polished tile with a dry surface, as above.

[0060] 5. Peeling strength test method of film D from a polished tile with a dry surface, from another film D with a dry surface, as above.

[0061] 6. Peeling strength test method of the inner layer of film E from a polished tile with a wet surface, from another film E with a wet surface, as above.

[0062] 7. Peeling strength test method of the inner layer of film F from a polished tile with a wet surface, from another film F with a wet surface, as above.

[0063] 8. Peeling strength test method of the inner layer of film G from a polished tile with a wet surface, from another film G with a wet surface, as above.

[0064] 9. Peeling strength test method of the inner layer of film H from a polished tile with a wet surface, from another film H with a wet surface, as above.

[0065] The test results are as follows.

[0066] Table 1. Peeling strength test

[0067] Film Packaging material Surface wetting / drying Peel force (N) Notes Film A inner side Polished tile piece Wet 0.23 Film A inner side Matte tile piece Wet 0.15 Film A inner side Glass piece Wet 0.25 Film A inner side Wood piece Wet 0.30 Film A inner side Iron piece Wet 0.09 Film A inner side Copper paper board Wet 0.33 Film A inner side Film A outer side Wet 0.62 Film A inner side Film B Wet 0.49 Film A inner side Polished tile piece Dry 0.0 Film B Polished tile piece Wet 0.0 Inner and outer sides separated Film C Polished tile piece Wet 0.05 Film C Polished tile piece Dry 0.28 Film D Polished tile piece Dry 0.0 Film D Film D Dry 0.21 Film E inner side Polished tile piece Wet 0.12 Inner and outer sides separated Film E inner side Film E outer side Wet 0.38 Inner and outer sides separated Film F inner side Polished tile piece Wet 0.17 Inner and outer sides separated Film F inner side Film F outer side Wet 0.44 Inner and outer sides separated Film G inner side Polished tile piece Wet 0.10 Inner and outer sides separated Film G inner side Film G outer side Wet 0.31 Inner and outer sides separated Film H inner side Polished tile piece Wet 0.25 Film H inner side Film H outer side Wet 0.65

[0068] From Table 1, it can be seen that the film A prepared in Example 1 of the present application can adhere to the surface of wetted objects including ceramic, glass, paperboard, wood chips and other materials, and there is a certain peeling force between the film and the packaged objects. The film A has no such adhesion on the surface of dry objects, and the difference in peeling force before and after wetting is conducive to the packaging personnel to choose whether to adhere according to the actual needs of the packaged objects. From the test results of film B, it can be seen that when PE (low density polyethylene) is selected as the outer film, the film layers between the inner and outer films are easy to separate. From the test results of film C, it can be seen that the present application has similar adhesion to common adhesive tapes, but the glue on the adhesive tape is not sticky after wetting, and the wet adhesion of the present application is essentially different from the adhesion of the adhesive tape. From the test results of film D, it can be seen that the commercially available PE preservative film is mainly self-adhesive and has almost no adhesion to other materials. From the test results of film E and film F, it can be seen that the film with only epoxy additive or only ethylene-acrylate-glycidyl methacrylate causes easy peeling between the inner and outer layers, resulting in a decrease in the peeling strength between the film and the packaged material.

Claims

1. A fully biodegradable film, characterized in that, It has a two-layer structure. The outer layer is a fully biodegradable polyester material modified with an epoxy modifier. The inner layer is a mixed material. By weight percentage, the raw materials of the inner layer mixed material include 50-90% polyvinyl alcohol, 5-20% plasticizer, 1.5-8% ethylene-acrylate-glycidyl methacrylate, and the remainder are other additives. The other additives are selected from one or more of antioxidants, opening agents, and inorganic powder fillers. The degree of alcoholysis of the polyvinyl alcohol is 78-99%, and the degree of polymerization is 30,000-170,000.

2. The thin film according to claim 1, characterized in that, The inner layer also includes a polyester-based fully biodegradable material modified with epoxy modifiers, which accounts for no more than 30% by weight.

3. The thin film according to claim 1 or 2, characterized in that, The epoxy-modified polyester fully biodegradable material is modified by using an epoxy-modified agent at a weight percentage of 0.4-0.8% to modify the polyester fully biodegradable material; the polyester fully biodegradable material is selected from one or two of the following materials: polybutylene adipate / terephthalate, polylactic acid, polypropylene carbonate, polybutylene succinate, polyglycolic acid, and polycaprolactone.

4. The thin film according to claim 3, characterized in that, The epoxy modifier is an oligomer with a molecular weight of 6000-8000 g / mol and an epoxy equivalent of 200-400 g / eq.

5. The thin film according to claim 1 or 2, characterized in that, The degree of alcoholysis of the polyvinyl alcohol is 78-88%.

6. The thin film according to claim 1 or 2, characterized in that, The plasticizer is glycerol or a compound plasticizer composed of glycerol and other plasticizers, wherein the other plasticizers are selected from one or more of ethylene glycol, polyethylene glycol, triethylene glycol, and 1,3-propanediol.

7. The thin film according to claim 1 or 2, characterized in that, The glycidyl methacrylate group in the ethylene-acrylate-glycidyl methacrylate has a weight percentage of 6-10%.

8. A method for preparing a thin film according to any one of claims 1-7, characterized in that, The raw materials are heated, melted, and co-extruded in multiple layers to prepare a film using one of the following methods: film blowing, casting, or calendering.

9. The preparation method according to claim 8, characterized in that, When preparing films using the thin film blow molding method, the specific steps are as follows: (1) Weigh out polyester fully biodegradable material and epoxy modifier by weight, melt blend them in a twin-screw extruder, extrude and granulate them and dry them to obtain epoxy modifier-modified polyester fully biodegradable material as outer layer material; (2) Weigh the raw materials by weight, mix the polyvinyl alcohol, plasticizer and other additives thoroughly in a high-speed mixer, melt blend them in a twin-screw extruder, and then mix them with ethylene-acrylate-glycidyl methacrylate at room temperature to obtain the inner layer material. Alternatively, weigh the raw materials by weight, and thoroughly mix the polyvinyl alcohol, the epoxy-modified polyester biodegradable material obtained in step 1), plasticizer and other additives in a high-speed mixer, then melt-blend them in a twin-screw extruder, and then mix them with ethylene-acrylate-glycidyl methacrylate at room temperature at high speed to obtain the inner layer material. (3) Add the outer layer material and the inner layer material into the double-layer extrusion blown film machine, blow the film, trim the edges, and roll it up to obtain the packaging film.

10. The application of the film according to any one of claims 1-7 in building materials, characterized in that, The inner surface of the membrane faces the building material and is in direct contact with it.

Images